Duplicate code is one of the most pungent code smells. A rule that is often used is to re-structure code once it is duplicated in three or more places.
Common duplication problems, and corresponding solutions are:
| 1 | <?php  | 
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| 7 | abstract class Enum  | 
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| 8 | { | 
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| 9 | /** @var Enum[] */  | 
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| 10 | private static $instances = [];  | 
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| 11 | /** @var \ReflectionClassConstant[] */  | 
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| 12 | private static $constReflections = [];  | 
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| 13 | /** @var \ReflectionClass[] */  | 
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| 14 | private static $reflections = [];  | 
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| 15 | /** @var string */  | 
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| 16 | private $name;  | 
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| 17 | |||
| 18 | /**  | 
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| 19 | * @param string $name  | 
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| 20 | */  | 
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| 21 | 3 | final private function __construct(string $name)  | 
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| 22 |     { | 
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| 23 | 3 | $this->name = $name;  | 
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| 24 | 3 | }  | 
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| 25 | |||
| 26 | /**  | 
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| 27 | * Creates enum instance with short static constructor  | 
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| 28 | *  | 
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| 29 | * @param string $name  | 
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| 30 | * @param array $arguments  | 
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| 31 | *  | 
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| 32 | * @return static  | 
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| 33 | *  | 
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| 34 | * @throws EnumException  | 
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| 35 | */  | 
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| 36 | 6 | final public static function __callStatic(string $name, array $arguments)  | 
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| 37 |     { | 
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| 38 | 6 | $const = static::getConstList();  | 
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| 39 | |||
| 40 | 6 |         if (!\in_array($name, $const, true)) { | 
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| 41 | 1 | throw EnumException::becauseUnknownMember(static::class, $name);  | 
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| 42 | }  | 
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| 43 | |||
| 44 | 5 | return static::createNamedInstance($name);  | 
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| 45 | }  | 
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| 46 | |||
| 47 | 7 | public static function getConstList(): array  | 
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| 48 |     { | 
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| 49 | 7 | return array_keys(self::getEnumReflection(static::class)->getConstants());  | 
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| 50 | }  | 
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| 51 | |||
| 52 | 5 | View Code Duplication | private static function getConstantReflection(string $class, string $name): \ReflectionClassConstant  | 
            
| 63 | |||
| 64 | 5 | private static function getConstKey(string $class, string $name): string  | 
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| 68 | |||
| 69 | 5 | private static function findParentClassForConst(string $name): string  | 
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| 73 | |||
| 74 | 7 | private static function getEnumReflection(string $class): \ReflectionClass  | 
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| 75 |     { | 
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| 76 | 7 |         if (!array_key_exists($class, self::$reflections)) { | 
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| 82 | |||
| 83 | /**  | 
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| 84 | * Create named enum instance  | 
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| 85 | *  | 
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| 86 | * @param string $name  | 
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| 87 | *  | 
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| 88 | * @return static  | 
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| 89 | */  | 
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| 90 | 5 | View Code Duplication | private static function createNamedInstance(string $name)  | 
            
| 102 | |||
| 103 | 1 | final public function getName(): string  | 
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| 107 | |||
| 108 | /**  | 
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| 109 |      * {@inheritdoc} | 
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| 110 | */  | 
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| 111 | 1 | final public function __toString(): string  | 
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| 115 | }  | 
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| 116 | 
Let’s assume you have a class which uses late-static binding:
}
The code above will run fine in your PHP runtime. However, if you now create a sub-class and call the
getSomeVariable()on that sub-class, you will receive a runtime error:In the case above, it makes sense to update
SomeClassto useselfinstead: